Bacteria identification on NPWT foams: clinical relevance or contamination?

• Objective: To compare and interpret the microbiological findings of tissue samples prior to and during negative pressure wound therapy (NPWT), as well as those of NPWT foams. • Method: A retrospective evaluation of 101 NPWT dressings (29 polyurethane, 72 polyvinylalcohol; 43 deeply inserted, 56 superficially, two combined deeply and superficially; 67 hardware present and 34 no hardware present) in 64 patients was conducted. All foam and tissue samples were cultured over a period of 7 days. Tissue and foam samples were incubated on blood agar plates and in tryptic soya broth. Positive results indicated a microbial growth with > 105 colony forming units (CFU)/ml. • Results: Total mean implantation period was 6 ± 2 days (2–14 days). On 39 foams (39%), at least one organism could be identified. While S. aureus and S. epidermidis were the most common organisms prior to NPWT, during therapy S. epidermidis and S. aureus were most frequently identified in the tissue samples, with E. faecalis and S. epidermidis ...